This clinical trial is focused on studying a new treatment for people with refractory angina, a condition where patients experience chest pain due to reduced blood flow to the heart, and traditional treatments like surgery or angioplasty are not possible. The treatment being tested is called AdsVEGF-D Delta N Delta C, which is a type of gene therapy. This therapy uses a modified virus, known as an adenovirus vector, to deliver a specific gene called vascular endothelial growth factor D (VEGF-D) directly to the heart. This gene is intended to help improve blood flow by encouraging the growth of new blood vessels.

The purpose of the study is to evaluate the safety and effectiveness of this gene therapy in patients with severe coronary artery disease who cannot undergo revascularization procedures. Participants in the study will receive either the gene therapy or a placebo, and neither the participants nor the researchers will know who receives which treatment. The treatment is administered through an injection directly into the heart.

Throughout the study, participants will be monitored to assess improvements in their ability to perform physical activities, such as walking, and any changes in their symptoms. The study aims to determine if the gene therapy can enhance the heart’s blood supply and improve the quality of life for those with refractory angina. The trial is expected to continue until the end of 2027.